Champion athletec Colin Jackson has enraged vegetarians by saying that everyone should eat meat to remain at their physical peak. His comments came after he took part in a month-long experiment for a BBC TV programme .

Jackson, a former world champion sprint hurdler and recent star of Strictly Come Dancing, said he felt 'physically weaker' after the month when he gave up meat. His claims are backed by leading sports scientists. His comments have reopened the debate over whether avoiding meat can damage health.

'I definitely think vegetarians are weaker,' Jackson said, after taking part in the TV series The Truth About Food. 'I could see I'd lost a little bit of muscle on my arms and shoulders. When I had to do tests afterwards, I knew I'd lost power.'

Asked whether vegetarians should eat meat, Jackson was emphatic. 'Definitely. They should have some type of meat whether it's fish or actual meat. Human beings are omnivores.'

The study, which will be broadcast on BBC2 on Thursday at 8pm, also asked six vegetarian sportswomen to eat meat to see how their physical performance changed compared with a control group who continued eating a vegetarian diet.

Although the study group was too small for any firm conclusions to be drawn, the programme's producer, Caroline Penry-Davey, described the results as 'anecdotally very interesting'.

Vanessa Curry, a teacher and martial arts expert from Perthshire, was required to eat meat twice a day. She described the transition after more than four years of vegetarianism as difficult.

'I found the first week quite hard - my tummy swelled and I felt nauseous - but I was interested in getting involved with something that would show if being a vegetarian did affect me,' she said. 'Some people find out I'm a veggie and with me being quite slender make the connection I'm not healthy. I wanted to prove being a veggie was not detrimental in any way to sporting performance.'

Her results told a different story: she showed an improvement in strength and stamina after eating meat. 'I was really surprised by the results; I didn't feel stronger or faster,' she confessed.

Professor Roger Harris, of Chichester University's Department of Sport, Exercise and Health Sciences, who ran the study, said micronutrients vital to muscle function - creatine and carnosine - are found only in meat and fish.

'There is some evidence to support the theory that vegetarians are weaker than they might be. They have lower levels of creatine and carnosine in their muscles than meat eaters. Vegetarians must make all of their own whereas meat eaters utilise what is available in their diet.' He said vegetarians were capable of outstanding athletic performance but added: 'In competitive athletes, their performance could be improved further if the levels of muscle carnosine and creatine were to be increased.'

Jackson's claims were rejected by Chris Olivant from the Vegetarian Society. 'If any professional sportsman were to diverge from his specialist diet without professional advice it would be sure to have some short-term effect,' he said.

'Perhaps Mr Jackson is not familiar with Edwin Moses, a long-time vegetarian, who won gold at the 400 metre hurdles at the 1976 and 1984 Olympics, set the world record at that distance four times, and won 107 consecutive finals?' He added: 'There are around 3m vegetarians in the UK and I doubt many of them will be changing their eating habits following Mr Jackson's advice.'